Search results for "MT"

Samtidskunst i skolen : En studie som inviterer elever til en konseptuell workshopspraksis

2019

Masteroppgave kunstfag KF500 - Universitetet i Agder 2019 Both from the elementary school education and the professional life, I have gained insight and an experience basis for commenting on the subject of arts and crafts. There are often techniques and crafts that are in focus. I miss howthe subject to a greater extentcanchallengestudent`s in critical thinking, playful exploration and reflection, especially with regards to visual art. This master thesis focuses on theseperspectives for teaching in the subject arts and crafts, and discuss contemporary art's place intheschool. The thesis can be viewed as a post in the discourse about the new curriculumforarts and crafts, scheduledtobe comple…

Ceļš: Latvijas Universitātes Teoloģijas fakultātes teoloģisks, reliģijpētniecisks un kultūrvēsturisks izdevums, Nr. 65

2015

Magnetic field driven micro-convection in the Hele-Shaw cell: the Brinkman model and its comparison with experiment

2015

International audience; The micro-convection caused by the ponderomotive forces of the self-magnetic field in a magnetic fluid is studied here both numerically and experimentally. The theoretical approach based on the general Brinkman model substantially improves the description with respect to the previously proposed Darcy model. The predictions of both models are here compared to finely controlled experiments. The Brinkman model, in contrast to the Darcy model, allows us to describe the formation of mushrooms on the plumes of the micro-convective flow and the width of the fingers. In the Brinkman approach, excellent quantitative agreement is also obtained for the finger velocity dynamics …

Tracking the time-evolution of the electron distribution function in Copper by femtosecond broadband optical spectroscopy

2019

Multitemperature models are nowadays often used to quantify the ultrafast electron-phonon (boson) relaxations and coupling strengths in advanced quantum solids. To test their applicability and limitations, we perform systematic studies of carrier relaxation dynamics in copper, a prototype system for which the two-temperature model (TTM) was initially considered. Using broadband time-resolved optical spectroscopy, we study the time evolution of the electron distribution function, $f(E)$, over a large range of excitation densities. Following intraband optical excitation, $f(E)$ is found to be athermal over several 100 fs, with a substantial part of the absorbed energy already being transferre…

The tensor of interaction of a two-level system with an arbitrary strain field

2007

The interaction between two-level systems (TLS) and strain fields in a solid is contained in the diagonal matrix element of the interaction hamiltonian, $\delta$, which, in general, has the expression $\delta=2[\gamma]:[S]$, with the tensor $[\gamma]$ describing the TLS ``deformability'' and $[S]$ being the symmetric strain tensor. We construct $[\gamma]$ on very general grounds, by associating to the TLS two objects: a direction, $\hat\bt$, and a forth rank tensor of coupling constants, $[[R]]$. Based on the method of construction and on the invariance of the expression of $\delta$ with respect to the symmetry transformation of the solid, we conclude that $[[R]]$ has the same structure as …

Spin-Wave Driven Bidirectional Domain Wall Motion in Kagome Antiferromagnets

2021

We predict a mechanism to controllably manipulate domain walls in kagome antiferromagnets via a single linearly polarized spin-wave source. We show by means of atomistic spin dynamics simulations of antiferromagnets with kagome structure that the speed and direction of the domain wall motion can be regulated by only tuning the frequency of the applied spin-wave. Starting from microscopics, we establish an effective action and derive the corresponding equations of motion for the spin-wave-driven domain wall. Our analytical calculations reveal that the coupling of two spin-wave modes inside the domain wall explains the frequency-dependent velocity of the spin texture. Such a highly tunable sp…

Sekcija “Dezinformācijas un sazvērestību radītie riski demokrātijai: Latvijas pieredzes pārlūkošana”: Kopsavilkumi : 2021. gada 25. un 26. februāris

2021

Latvijas Zinātnes padomes fundamentālo un lietišķo projektu programmas projekts “Dezinformācijas un sazvērestību radītie riski demokrātijai: Latvijas pieredzes pārlūkošana” (lzp-2019/1-0278)

Effects of high-pressure on the structural, vibrational, and electronic properties of monazite-type PbCrO4

2012

We have performed an experimental study of the crystal structure, lattice dynamics, and optical properties of PbCrO 4 (the mineral crocoite) at ambient and high pressures. In particular, the crystal structure, Raman-active phonons, and electronic band gap have been accurately determined. X-ray-diffraction, Raman, and optical absorption experiments have allowed us also to completely characterize two pressure-induced structural phase transitions. The first transition is from a monoclinic structure to another monoclinic structure. It maintains the symmetry of the crystal but has important consequences in the physical properties; among others, a band-gap collapse is induced. The second one invo…

Exciton Interactions and Femtosecond Relaxation in Chlorophyll a−Water and Chlorophyll a−Dioxane Aggregates

1998

Chlorophyll a (Chl a) in hydrocarbon solution with a small amount of dioxane or water shows red-shifted absorption bands at 686 nm and at 700 nm (dioxane) and at 745 nm (water), indicative of self-organized aggregate structures in solution. To study the relationship between the structure and spectral properties of the aggregates, several one-dimensional model structures of Chl a−dioxane and Chl a−water aggregates were computed by the molecular mechanics method. Three overall structures ranging from stick to a ring shape were energetically favored for the dioxane system. All these structures contain structural heterogeneity that consists of repeating dimers that further form tetramer substru…

Quasinodal lines in rhombohedral magnetic materials

2021

A well-established result in condensed matter physics states that materials crystallizing in symmetry groups containing glide reflection symmetries possess nodal lines on the energy bands. These nodal lines are topologically protected and appear on the fixed planes of the reflection in reciprocal space. In the presence of inversion symmetry, the energy bands are degenerate and the nodal lines on the fixed plane may hybridize or may cross. In the former case, the crossing is avoided, thus producing lines on reciprocal space where the energy gap is small, and in the latter, the nodal lines will endure, thus producing Dirac or double nodal lines. In addition, if the material crystallizes in a …